auth2-chall.c - third_party/openssh-portable - Git at Google

 /* $OpenBSD: auth2-chall.c,v 1.50 2018/07/11 18:55:11 markus Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2001 Per Allansson.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "includes.h"

 #include <sys/types.h>

 #include <stdarg.h>
 #include <stdio.h>
 #include <string.h>

 #include "xmalloc.h"
 #include "ssh2.h"
 #include "sshkey.h"
 #include "hostfile.h"
 #include "auth.h"
 #include "sshbuf.h"
 #include "packet.h"
 #include "dispatch.h"
 #include "ssherr.h"
 #include "log.h"
 #include "misc.h"
 #include "servconf.h"

 /* import */
 extern ServerOptions options;

 static int auth2_challenge_start(struct ssh *);
 static int send_userauth_info_request(struct ssh *);
 static int input_userauth_info_response(int, u_int32_t, struct ssh *);

 #ifdef BSD_AUTH
 extern KbdintDevice bsdauth_device;
 #else
 #ifdef USE_PAM
 extern KbdintDevice sshpam_device;
 #endif
 #endif

 KbdintDevice *devices[] = {
 #ifdef BSD_AUTH
 	&bsdauth_device,
 #else
 #ifdef USE_PAM
 	&sshpam_device,
 #endif
 #endif
 	NULL
 };

 typedef struct KbdintAuthctxt KbdintAuthctxt;
 struct KbdintAuthctxt
 {
 	char *devices;
 	void *ctxt;
 	KbdintDevice *device;
 	u_int nreq;
 	u_int devices_done;
 };

 #ifdef USE_PAM
 void
 remove_kbdint_device(const char *devname)
 {
 	int i, j;

 	for (i = 0; devices[i] != NULL; i++)
 		if (strcmp(devices[i]->name, devname) == 0) {
 			for (j = i; devices[j] != NULL; j++)
 				devices[j] = devices[j+1];
 			i--;
 		}
 }
 #endif

 static KbdintAuthctxt *
 kbdint_alloc(const char *devs)
 {
 	KbdintAuthctxt *kbdintctxt;
 	struct sshbuf *b;
 	int i, r;

 #ifdef USE_PAM
 	if (!options.use_pam)
 		remove_kbdint_device("pam");
 #endif

 	kbdintctxt = xcalloc(1, sizeof(KbdintAuthctxt));
 	if (strcmp(devs, "") == 0) {
 		if ((b = sshbuf_new()) == NULL)
 			fatal("%s: sshbuf_new failed", __func__);
 		for (i = 0; devices[i]; i++) {
 			if ((r = sshbuf_putf(b, "%s%s",
 			    sshbuf_len(b) ? "," : "", devices[i]->name)) != 0)
 				fatal("%s: buffer error: %s",
 				    __func__, ssh_err(r));
 		}
 		if ((kbdintctxt->devices = sshbuf_dup_string(b)) == NULL)
 			fatal("%s: sshbuf_dup_string failed", __func__);
 		sshbuf_free(b);
 	} else {
 		kbdintctxt->devices = xstrdup(devs);
 	}
 	debug("kbdint_alloc: devices '%s'", kbdintctxt->devices);
 	kbdintctxt->ctxt = NULL;
 	kbdintctxt->device = NULL;
 	kbdintctxt->nreq = 0;

 	return kbdintctxt;
 }
 static void
 kbdint_reset_device(KbdintAuthctxt *kbdintctxt)
 {
 	if (kbdintctxt->ctxt) {
 		kbdintctxt->device->free_ctx(kbdintctxt->ctxt);
 		kbdintctxt->ctxt = NULL;
 	}
 	kbdintctxt->device = NULL;
 }
 static void
 kbdint_free(KbdintAuthctxt *kbdintctxt)
 {
 	if (kbdintctxt->device)
 		kbdint_reset_device(kbdintctxt);
 	free(kbdintctxt->devices);
 	explicit_bzero(kbdintctxt, sizeof(*kbdintctxt));
 	free(kbdintctxt);
 }
 /* get next device */
 static int
 kbdint_next_device(Authctxt *authctxt, KbdintAuthctxt *kbdintctxt)
 {
 	size_t len;
 	char *t;
 	int i;

 	if (kbdintctxt->device)
 		kbdint_reset_device(kbdintctxt);
 	do {
 		len = kbdintctxt->devices ?
 		    strcspn(kbdintctxt->devices, ",") : 0;

 		if (len == 0)
 			break;
 		for (i = 0; devices[i]; i++) {
 			if ((kbdintctxt->devices_done & (1 << i)) != 0 ||
 			    !auth2_method_allowed(authctxt,
 			    "keyboard-interactive", devices[i]->name))
 				continue;
 			if (strncmp(kbdintctxt->devices, devices[i]->name,
 			    len) == 0) {
 				kbdintctxt->device = devices[i];
 				kbdintctxt->devices_done |= 1 << i;
 			}
 		}
 		t = kbdintctxt->devices;
 		kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;
 		free(t);
 		debug2("kbdint_next_device: devices %s", kbdintctxt->devices ?
 		    kbdintctxt->devices : "<empty>");
 	} while (kbdintctxt->devices && !kbdintctxt->device);

 	return kbdintctxt->device ? 1 : 0;
 }

 /*
  * try challenge-response, set authctxt->postponed if we have to
  * wait for the response.
  */
 int
 auth2_challenge(struct ssh *ssh, char *devs)
 {
 	Authctxt *authctxt = ssh->authctxt;
 	debug("auth2_challenge: user=%s devs=%s",
 	    authctxt->user ? authctxt->user : "<nouser>",
 	    devs ? devs : "<no devs>");

 	if (authctxt->user == NULL || !devs)
 		return 0;
 	if (authctxt->kbdintctxt == NULL)
 		authctxt->kbdintctxt = kbdint_alloc(devs);
 	return auth2_challenge_start(ssh);
 }

 /* unregister kbd-int callbacks and context */
 void
 auth2_challenge_stop(struct ssh *ssh)
 {
 	Authctxt *authctxt = ssh->authctxt;
 	/* unregister callback */
 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
 	if (authctxt->kbdintctxt != NULL) {
 		kbdint_free(authctxt->kbdintctxt);
 		authctxt->kbdintctxt = NULL;
 	}
 }

 /* side effect: sets authctxt->postponed if a reply was sent*/
 static int
 auth2_challenge_start(struct ssh *ssh)
 {
 	Authctxt *authctxt = ssh->authctxt;
 	KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt;

 	debug2("auth2_challenge_start: devices %s",
 	    kbdintctxt->devices ?  kbdintctxt->devices : "<empty>");

 	if (kbdint_next_device(authctxt, kbdintctxt) == 0) {
 		auth2_challenge_stop(ssh);
 		return 0;
 	}
 	debug("auth2_challenge_start: trying authentication method '%s'",
 	    kbdintctxt->device->name);

 	if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) {
 		auth2_challenge_stop(ssh);
 		return 0;
 	}
 	if (send_userauth_info_request(ssh) == 0) {
 		auth2_challenge_stop(ssh);
 		return 0;
 	}
 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE,
 	    &input_userauth_info_response);

 	authctxt->postponed = 1;
 	return 0;
 }

 static int
 send_userauth_info_request(struct ssh *ssh)
 {
 	Authctxt *authctxt = ssh->authctxt;
 	KbdintAuthctxt *kbdintctxt;
 	char *name, *instr, **prompts;
 	u_int r, i, *echo_on;

 	kbdintctxt = authctxt->kbdintctxt;
 	if (kbdintctxt->device->query(kbdintctxt->ctxt,
 	    &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on))
 		return 0;

 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST)) != 0 ||
 	    (r = sshpkt_put_cstring(ssh, name)) != 0 ||
 	    (r = sshpkt_put_cstring(ssh, instr)) != 0 ||
 	    (r = sshpkt_put_cstring(ssh, "")) != 0 ||	/* language not used */
 	    (r = sshpkt_put_u32(ssh, kbdintctxt->nreq)) != 0)
 		fatal("%s: %s", __func__, ssh_err(r));
 	for (i = 0; i < kbdintctxt->nreq; i++) {
 		if ((r = sshpkt_put_cstring(ssh, prompts[i])) != 0 ||
 		    (r = sshpkt_put_u8(ssh, echo_on[i])) != 0)
 			fatal("%s: %s", __func__, ssh_err(r));
 	}
 	if ((r = sshpkt_send(ssh)) != 0 ||
 	    (r = ssh_packet_write_wait(ssh)) != 0)
 		fatal("%s: %s", __func__, ssh_err(r));

 	for (i = 0; i < kbdintctxt->nreq; i++)
 		free(prompts[i]);
 	free(prompts);
 	free(echo_on);
 	free(name);
 	free(instr);
 	return 1;
 }

 static int
 input_userauth_info_response(int type, u_int32_t seq, struct ssh *ssh)
 {
 	Authctxt *authctxt = ssh->authctxt;
 	KbdintAuthctxt *kbdintctxt;
 	int authenticated = 0, res;
 	int r;
 	u_int i, nresp;
 	const char *devicename = NULL;
 	char **response = NULL;

 	if (authctxt == NULL)
 		fatal("input_userauth_info_response: no authctxt");
 	kbdintctxt = authctxt->kbdintctxt;
 	if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL)
 		fatal("input_userauth_info_response: no kbdintctxt");
 	if (kbdintctxt->device == NULL)
 		fatal("input_userauth_info_response: no device");

 	authctxt->postponed = 0;	/* reset */
 	if ((r = sshpkt_get_u32(ssh, &nresp)) != 0)
 		fatal("%s: %s", __func__, ssh_err(r));
 	if (nresp != kbdintctxt->nreq)
 		fatal("input_userauth_info_response: wrong number of replies");
 	if (nresp > 100)
 		fatal("input_userauth_info_response: too many replies");
 	if (nresp > 0) {
 		response = xcalloc(nresp, sizeof(char *));
 		for (i = 0; i < nresp; i++)
 			if ((r = sshpkt_get_cstring(ssh, &response[i],
 			    NULL)) != 0)
 				fatal("%s: %s", __func__, ssh_err(r));
 	}
 	if ((r = sshpkt_get_end(ssh)) != 0)
 		fatal("%s: %s", __func__, ssh_err(r));

 	res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response);

 	for (i = 0; i < nresp; i++) {
 		explicit_bzero(response[i], strlen(response[i]));
 		free(response[i]);
 	}
 	free(response);

 	switch (res) {
 	case 0:
 		/* Success! */
 		authenticated = authctxt->valid ? 1 : 0;
 		break;
 	case 1:
 		/* Authentication needs further interaction */
 		if (send_userauth_info_request(ssh) == 1)
 			authctxt->postponed = 1;
 		break;
 	default:
 		/* Failure! */
 		break;
 	}
 	devicename = kbdintctxt->device->name;
 	if (!authctxt->postponed) {
 		if (authenticated) {
 			auth2_challenge_stop(ssh);
 		} else {
 			/* start next device */
 			/* may set authctxt->postponed */
 			auth2_challenge_start(ssh);
 		}
 	}
 	userauth_finish(ssh, authenticated, "keyboard-interactive",
 	    devicename);
 	return 0;
 }

 void
 privsep_challenge_enable(void)
 {
 #if defined(BSD_AUTH) || defined(USE_PAM)
 	int n = 0;
 #endif
 #ifdef BSD_AUTH
 	extern KbdintDevice mm_bsdauth_device;
 #endif
 #ifdef USE_PAM
 	extern KbdintDevice mm_sshpam_device;
 #endif

 #ifdef BSD_AUTH
 	devices[n++] = &mm_bsdauth_device;
 #else
 #ifdef USE_PAM
 	devices[n++] = &mm_sshpam_device;
 #endif
 #endif
 }
	/* $OpenBSD: auth2-chall.c,v 1.50 2018/07/11 18:55:11 markus Exp $ */
	/*
	* Copyright (c) 2001 Markus Friedl. All rights reserved.
	* Copyright (c) 2001 Per Allansson. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "includes.h"

	#include <sys/types.h>

	#include <stdarg.h>
	#include <stdio.h>
	#include <string.h>

	#include "xmalloc.h"
	#include "ssh2.h"
	#include "sshkey.h"
	#include "hostfile.h"
	#include "auth.h"
	#include "sshbuf.h"
	#include "packet.h"
	#include "dispatch.h"
	#include "ssherr.h"
	#include "log.h"
	#include "misc.h"
	#include "servconf.h"

	/* import */
	extern ServerOptions options;

	static int auth2_challenge_start(struct ssh *);
	static int send_userauth_info_request(struct ssh *);
	static int input_userauth_info_response(int, u_int32_t, struct ssh *);

	#ifdef BSD_AUTH
	extern KbdintDevice bsdauth_device;
	#else
	#ifdef USE_PAM
	extern KbdintDevice sshpam_device;
	#endif
	#endif

	KbdintDevice *devices[] = {
	#ifdef BSD_AUTH
	&bsdauth_device,
	#else
	#ifdef USE_PAM
	&sshpam_device,
	#endif
	#endif
	NULL
	};

	typedef struct KbdintAuthctxt KbdintAuthctxt;
	struct KbdintAuthctxt
	{
	char *devices;
	void *ctxt;
	KbdintDevice *device;
	u_int nreq;
	u_int devices_done;
	};

	#ifdef USE_PAM
	void
	remove_kbdint_device(const char *devname)
	{
	int i, j;

	for (i = 0; devices[i] != NULL; i++)
	if (strcmp(devices[i]->name, devname) == 0) {
	for (j = i; devices[j] != NULL; j++)
	devices[j] = devices[j+1];
	i--;
	}
	}
	#endif

	static KbdintAuthctxt *
	kbdint_alloc(const char *devs)
	{
	KbdintAuthctxt *kbdintctxt;
	struct sshbuf *b;
	int i, r;

	#ifdef USE_PAM
	if (!options.use_pam)
	remove_kbdint_device("pam");
	#endif

	kbdintctxt = xcalloc(1, sizeof(KbdintAuthctxt));
	if (strcmp(devs, "") == 0) {
	if ((b = sshbuf_new()) == NULL)
	fatal("%s: sshbuf_new failed", __func__);
	for (i = 0; devices[i]; i++) {
	if ((r = sshbuf_putf(b, "%s%s",
	sshbuf_len(b) ? "," : "", devices[i]->name)) != 0)
	fatal("%s: buffer error: %s",
	__func__, ssh_err(r));
	}
	if ((kbdintctxt->devices = sshbuf_dup_string(b)) == NULL)
	fatal("%s: sshbuf_dup_string failed", __func__);
	sshbuf_free(b);
	} else {
	kbdintctxt->devices = xstrdup(devs);
	}
	debug("kbdint_alloc: devices '%s'", kbdintctxt->devices);
	kbdintctxt->ctxt = NULL;
	kbdintctxt->device = NULL;
	kbdintctxt->nreq = 0;

	return kbdintctxt;
	}
	static void
	kbdint_reset_device(KbdintAuthctxt *kbdintctxt)
	{
	if (kbdintctxt->ctxt) {
	kbdintctxt->device->free_ctx(kbdintctxt->ctxt);
	kbdintctxt->ctxt = NULL;
	}
	kbdintctxt->device = NULL;
	}
	static void
	kbdint_free(KbdintAuthctxt *kbdintctxt)
	{
	if (kbdintctxt->device)
	kbdint_reset_device(kbdintctxt);
	free(kbdintctxt->devices);
	explicit_bzero(kbdintctxt, sizeof(*kbdintctxt));
	free(kbdintctxt);
	}
	/* get next device */
	static int
	kbdint_next_device(Authctxt authctxt, KbdintAuthctxt kbdintctxt)
	{
	size_t len;
	char *t;
	int i;

	if (kbdintctxt->device)
	kbdint_reset_device(kbdintctxt);
	do {
	len = kbdintctxt->devices ?
	strcspn(kbdintctxt->devices, ",") : 0;

	if (len == 0)
	break;
	for (i = 0; devices[i]; i++) {
	if ((kbdintctxt->devices_done & (1 << i)) != 0 \|\|
	!auth2_method_allowed(authctxt,
	"keyboard-interactive", devices[i]->name))
	continue;
	if (strncmp(kbdintctxt->devices, devices[i]->name,
	len) == 0) {
	kbdintctxt->device = devices[i];
	kbdintctxt->devices_done \|= 1 << i;
	}
	}
	t = kbdintctxt->devices;
	kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;
	free(t);
	debug2("kbdint_next_device: devices %s", kbdintctxt->devices ?
	kbdintctxt->devices : "<empty>");
	} while (kbdintctxt->devices && !kbdintctxt->device);

	return kbdintctxt->device ? 1 : 0;
	}

	/*
	* try challenge-response, set authctxt->postponed if we have to
	* wait for the response.
	*/
	int
	auth2_challenge(struct ssh ssh, char devs)
	{
	Authctxt *authctxt = ssh->authctxt;
	debug("auth2_challenge: user=%s devs=%s",
	authctxt->user ? authctxt->user : "<nouser>",
	devs ? devs : "<no devs>");

	if (authctxt->user == NULL \|\| !devs)
	return 0;
	if (authctxt->kbdintctxt == NULL)
	authctxt->kbdintctxt = kbdint_alloc(devs);
	return auth2_challenge_start(ssh);
	}

	/* unregister kbd-int callbacks and context */
	void
	auth2_challenge_stop(struct ssh *ssh)
	{
	Authctxt *authctxt = ssh->authctxt;
	/* unregister callback */
	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
	if (authctxt->kbdintctxt != NULL) {
	kbdint_free(authctxt->kbdintctxt);
	authctxt->kbdintctxt = NULL;
	}
	}

	/* side effect: sets authctxt->postponed if a reply was sent*/
	static int
	auth2_challenge_start(struct ssh *ssh)
	{
	Authctxt *authctxt = ssh->authctxt;
	KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt;

	debug2("auth2_challenge_start: devices %s",
	kbdintctxt->devices ? kbdintctxt->devices : "<empty>");

	if (kbdint_next_device(authctxt, kbdintctxt) == 0) {
	auth2_challenge_stop(ssh);
	return 0;
	}
	debug("auth2_challenge_start: trying authentication method '%s'",
	kbdintctxt->device->name);

	if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) {
	auth2_challenge_stop(ssh);
	return 0;
	}
	if (send_userauth_info_request(ssh) == 0) {
	auth2_challenge_stop(ssh);
	return 0;
	}
	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE,
	&input_userauth_info_response);

	authctxt->postponed = 1;
	return 0;
	}

	static int
	send_userauth_info_request(struct ssh *ssh)
	{
	Authctxt *authctxt = ssh->authctxt;
	KbdintAuthctxt *kbdintctxt;
	char name, instr, **prompts;
	u_int r, i, *echo_on;

	kbdintctxt = authctxt->kbdintctxt;
	if (kbdintctxt->device->query(kbdintctxt->ctxt,
	&name, &instr, &kbdintctxt->nreq, &prompts, &echo_on))
	return 0;

	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST)) != 0 \|\|
	(r = sshpkt_put_cstring(ssh, name)) != 0 \|\|
	(r = sshpkt_put_cstring(ssh, instr)) != 0 \|\|
	(r = sshpkt_put_cstring(ssh, "")) != 0 \|\| /* language not used */
	(r = sshpkt_put_u32(ssh, kbdintctxt->nreq)) != 0)
	fatal("%s: %s", __func__, ssh_err(r));
	for (i = 0; i < kbdintctxt->nreq; i++) {
	if ((r = sshpkt_put_cstring(ssh, prompts[i])) != 0 \|\|
	(r = sshpkt_put_u8(ssh, echo_on[i])) != 0)
	fatal("%s: %s", __func__, ssh_err(r));
	}
	if ((r = sshpkt_send(ssh)) != 0 \|\|
	(r = ssh_packet_write_wait(ssh)) != 0)
	fatal("%s: %s", __func__, ssh_err(r));

	for (i = 0; i < kbdintctxt->nreq; i++)
	free(prompts[i]);
	free(prompts);
	free(echo_on);
	free(name);
	free(instr);
	return 1;
	}

	static int
	input_userauth_info_response(int type, u_int32_t seq, struct ssh *ssh)
	{
	Authctxt *authctxt = ssh->authctxt;
	KbdintAuthctxt *kbdintctxt;
	int authenticated = 0, res;
	int r;
	u_int i, nresp;
	const char *devicename = NULL;
	char **response = NULL;

	if (authctxt == NULL)
	fatal("input_userauth_info_response: no authctxt");
	kbdintctxt = authctxt->kbdintctxt;
	if (kbdintctxt == NULL \|\| kbdintctxt->ctxt == NULL)
	fatal("input_userauth_info_response: no kbdintctxt");
	if (kbdintctxt->device == NULL)
	fatal("input_userauth_info_response: no device");

	authctxt->postponed = 0; /* reset */
	if ((r = sshpkt_get_u32(ssh, &nresp)) != 0)
	fatal("%s: %s", __func__, ssh_err(r));
	if (nresp != kbdintctxt->nreq)
	fatal("input_userauth_info_response: wrong number of replies");
	if (nresp > 100)
	fatal("input_userauth_info_response: too many replies");
	if (nresp > 0) {
	response = xcalloc(nresp, sizeof(char *));
	for (i = 0; i < nresp; i++)
	if ((r = sshpkt_get_cstring(ssh, &response[i],
	NULL)) != 0)
	fatal("%s: %s", __func__, ssh_err(r));
	}
	if ((r = sshpkt_get_end(ssh)) != 0)
	fatal("%s: %s", __func__, ssh_err(r));

	res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response);

	for (i = 0; i < nresp; i++) {
	explicit_bzero(response[i], strlen(response[i]));
	free(response[i]);
	}
	free(response);

	switch (res) {
	case 0:
	/* Success! */
	authenticated = authctxt->valid ? 1 : 0;
	break;
	case 1:
	/* Authentication needs further interaction */
	if (send_userauth_info_request(ssh) == 1)
	authctxt->postponed = 1;
	break;
	default:
	/* Failure! */
	break;
	}
	devicename = kbdintctxt->device->name;
	if (!authctxt->postponed) {
	if (authenticated) {
	auth2_challenge_stop(ssh);
	} else {
	/* start next device */
	/* may set authctxt->postponed */
	auth2_challenge_start(ssh);
	}
	}
	userauth_finish(ssh, authenticated, "keyboard-interactive",
	devicename);
	return 0;
	}

	void
	privsep_challenge_enable(void)
	{
	#if defined(BSD_AUTH) \|\| defined(USE_PAM)
	int n = 0;
	#endif
	#ifdef BSD_AUTH
	extern KbdintDevice mm_bsdauth_device;
	#endif
	#ifdef USE_PAM
	extern KbdintDevice mm_sshpam_device;
	#endif

	#ifdef BSD_AUTH
	devices[n++] = &mm_bsdauth_device;
	#else
	#ifdef USE_PAM
	devices[n++] = &mm_sshpam_device;
	#endif
	#endif
	}